Johnson says she expects most of the principals to know by Wednesday who stays and who goes.

"While I know it may be uncomfortable for people to reapply for their jobs and recommit, we also want them to examine their practice and make sure that they are the best teachers to serve these schools and to serve the students who need the help the most," Johnson said.

Johnson says teachers who aren't selected to stay might be eligible for jobs at other Boston schools.

At the same time, however, she is urging principals to identify individuals who are simply not right for their teaching jobs.

"We've taken real steps this year to identify teachers and try to distinguish between the teachers who should not be in the profession and the teachers who may be in the profession but need additional training and support," Johnson said.

This program aired on April 27, 2010. The audio for this program is not available.